8th Grade · Functions
Function
8.F.A.1
Definition
A rule that assigns to each input exactly one output. No input may produce more than one output.
Examples
- f(x) = 2x + 1: input x=3 gives exactly one output, 7.
- An input pointing to two different outputs is NOT a function.
Key rule
Every input must map to exactly one output for it to be a function.
Memory hook
One input, one output — always.